The present invention is directed to improved infrared or red light sensitive migration imaging members. One embodiment of the present invention is directed to a migration imaging member comprising a substrate and a softenable layer, said softenable layer comprising a softenable material, a pigment predominantly sensitive to infrared or red light radiation, and a migration marking material predominantly sensitive to radiation at a wavelength other than that to which the infrared or red light radiation sensitive pigment is sensitive contained at least at or near the surface of the softenable layer spaced from the substrate. Another embodiment of the present invention is directed to a migration imaging process which comprises the steps of (A) providing a migration imaging member comprising a substrate and a softenable layer, said softenable layer comprising a softenable material, a pigment predominantly sensitive to infrared or red light radiation, and a migration marking material predominantly sensitive to radiation at a wavelength other than that to which the infrared or red light radiation sensitive pigment is sensitive contained at least at or near the surface of the softenable layer spaced from the substrate; (B) uniformly charging the imaging member; (C) subsequent to step B, exposing the charged imaging member to infrared or red light radiation at a wavelength to which the infrared or red light radiation sensitive pigment is sensitive in an imagewise pattern, thereby forming an electrostatic latent image on the imaging member; (D) subsequent to step B, uniformly exposing the imaging member to activating radiation at a wavelength to which the migration marking material is sensitive; and (E) subsequent to steps C and D, causing the softenable material to soften, thereby enabling the migration marking material to migrate through the softenable material toward the substrate in an imagewise pattern.
Migration imaging systems capable of producing high quality images of high optical contrast density and high resolution have been developed. Such migration imaging systems are disclosed in, for example, U.S. Pat. No. 3,975,195 (Goffe), U.S. Pat. No. 3,909,262 (Goffe et al.), U.S. Pat. No. 4,536,457 (Tam), U.S. Pat. No. 4,536,458 (Ng), U.S. Pat. No. 4,013,462 (Goffe et al.), and "Migration Imaging Mechanisms, Exploitation, and Future Prospects of Unique Photographic Technologies, XDM and AMEN", P. S. Vincett, G. J. Kovacs, M. C. Tam, A. L. Pundsack, and P. H. Soden, Journal of Imaging Science 30 (4) July/August, pp. 183-191 (1986), the disclosures of each of which are totally incorporated herein by reference. Migration imaging members containing charge transport materials in the softenable layer are also known, and are disclosed, for example, in U.S. Pat. No. 4,536,457 (Tam) and U.S. Pat. No. 4,536,458 (Ng). In a typical embodiment of these migration imaging systems, a migration imaging member comprising a substrate, a layer of softenable material, and photosensitive marking material is imaged by first forming a latent image by electrically charging the member and exposing the charged member to a pattern of activating electromagnetic radiation such as light. Where the photosensitive marking material is originally in the form of a fracturable layer contiguous with the upper surface of the softenable layer, the marking particles in the exposed area of the member migrate in depth toward the substrate when the member is developed by softening the softenable layer.
The expression "softenable" as used herein is intended to mean any material which can be rendered more permeable, thereby enabling particles to migrate through its bulk. Conventionally, changing the permeability of such material or reducing its resistance to migration of migration marking material is accomplished by dissolving, swelling, melting, or softening, by techniques, for example, such as contacting with heat, vapors, partial solvents, solvent vapors, solvents, and combinations thereof, or by otherwise reducing the viscosity of the softenable material by any suitable means.
The expression "fracturable" layer or material as used herein means any layer or material which is capable of breaking up during development, thereby permitting portions of the layer to migrate toward the substrate or to be otherwise removed. The fracturable layer is preferably particulate in the various embodiments of the migration imaging members. Such fracturable layers of marking material are typically contiguous to the surface of the softenable layer spaced apart from the substrate, and such fracturable layers can be substantially or wholly embedded in the softenable layer in various embodiments of the imaging members.
The expression "contiguous" as used herein is intended to mean in actual contact, touching, also, near, though not in contact, and adjoining, and is intended to describe generically the relationship of the fracturable layer of marking material in the softenable layer with the surface of the softenable layer spaced apart from the substrate.
The expression "optically sign-retained" as used herein is intended to mean that the dark (higher optical density) and light (lower optical density) areas of the visible image formed on the migration imaging member correspond to the dark and light areas of the illuminating electromagnetic radiation pattern.
The expression "optically sign-reversed" as used herein is intended to mean that the dark areas of the image formed on the migration imaging member correspond to the light areas of the illuminating electromagnetic radiation pattern and the light areas of the image formed on the migration imaging member correspond to the dark areas of the illuminating electromagnetic radiation pattern.
The expression "optical contrast density" as used herein is intended to mean the difference between maximum optical density (D.sub.max) and minimum optical density (D.sub.min) of an image. Optical density is measured for the purpose of this invention by diffuse densitometers with a blue Wratten No. 47 filter. The expression "optical density" as used herein is intended to mean "transmission optical density" and is represented by the formula: EQU D=log.sub.10 [I.sub.o /I]
where l is the transmitted light intensity and l.sub.o is the incident light intensity. For the purpose of this invention, all values of transmission optical density given in this invention include the substrate density of about 0.2 which is the typical density of a metallized polyester substrate.
There are various other systems for forming such images, wherein non-photosensitive or inert marking materials are arranged in the aforementioned fracturable layers, or dispersed throughout the softenable layer, as described in the aforementioned patents, which also disclose a variety of methods which can be used to form latent images upon migration imaging members.
Various means for developing the latent images can be used for migration imaging systems. These development methods include solvent wash away, solvent vapor softening, heat softening, and combinations of these methods, as well as any other method which changes the resistance of the softenable material to the migration of particulate marking material through the softenable layer to allow imagewise migration of the particles in depth toward the substrate. In the solvent wash away or meniscus development method, the migration marking material in the light struck region migrates toward the substrate through the softenable layer, which is softened and dissolved, and repacks into a more or less monolayer configuration. In migration imaging films supported by transparent substrates alone, this region exhibits a maximum optical density which can be as high as the initial optical density of the unprocessed film. On the other hand, the migration marking material in the unexposed region is substantially washed away and this region exhibits a minimum optical density which is essentially the optical density of the substrate alone. Therefore, the image sense of the developed image is optically sign reversed. Various methods and materials and combinations thereof have previously been used to fix such unfixed migration images. One method is to overcoat the image with a transparent abrasion resistant polymer by solution coating techniques. In the heat or vapor softening developing modes, the migration marking material in the light struck region disperses in the depth of the softenable layer after development and this region exhibits D.sub.min which is typically in the range of 0.6 to 0.7. This relatively high D.sub.min is a direct consequence of the depthwise dispersion of the otherwise unchanged migration marking material. On the other hand, the migration marking material in the unexposed region does not migrate and substantially remains in the original configuration, i.e. a monolayer. In known migration imaging films supported by transparent substrates, this region exhibits a maximum optical density (D.sub.max) of about 1.8 to 1.9. Therefore, the image sense of the heat or vapor developed images is optically sign-retained.
Techniques have been devised to permit optically sign-reversed imaging with vapor development, but these techniques are generally complex and require critically controlled processing conditions. An example of such techniques can be found in U.S. Pat. No. 3,795,512, the disclosure of which is totally incorporated herein by reference.
For many imaging applications, it is desirable to produce negative images from a positive original or positive images from a negative original (optically sign-reversing imaging), preferably with low minimum optical density. Although the meniscus or solvent wash away development method produces optically sign-reversed images with low minimum optical density, it entails removal of materials from the migration imaging member, leaving the migration image largely or totally unprotected from abrasion. Although various methods and materials have previously been used to overcoat such unfixed migration images, the post-development overcoating step can be impractically costly and inconvenient for the end users. Additionally, disposal of the effluents washed from the migration imaging member during development can also be very costly.
The background portions of an imaged member can sometimes be transparentized by means of an agglomeration and coalescence effect. In this system, an imaging member comprising a softenable layer containing a fracturable layer of electrically photosensitive migration marking material is imaged in one process mode by electrostatically charging the member, exposing the member to an imagewise pattern of activating electromagnetic radiation, and softening the softenable layer by exposure for a few seconds to a solvent vapor thereby causing a selective migration in depth of the migration material in the softenable layer in the areas which were previously exposed to the activating radiation. The vapor developed image is then subjected to a heating step. Since the exposed particles gain a substantial net charge (typically 85 to 90 percent of the deposited surface charge) as a result of light exposure, they migrate substantially in depth in the softenable layer towards the substrate when exposed to a solvent vapor, thus causing a drastic reduction in optical density. The optical density in this region is typically in the region of 0.7 to 0.9 (including the substrate density of about 0.2) after vapor exposure, compared with an initial value of 1.8 to 1.9 (including the substrate density of about 0.2). In the unexposed region, the surface charge becomes discharged due to vapor exposure. The subsequent heating step causes the unmigrated, uncharged migration material in unexposed areas to agglomerate or flocculate, often accompanied by coalescence of the marking material particles, thereby resulting in a migration image of very low minimum optical density (in the unexposed areas) in the 0.25 to 0.35 range. Thus, the contrast density of the final image is typically in the range of 0.35 to 0.65. Alternatively, the migration image can be formed by heat followed by exposure to solvent vapors and a second heating step which also results in a migration image with very low minimum optical density. In this imaging system as well as in the previously described heat or vapor development techniques, the softenable layer remains substantially intact after development, with the image being self-fixed because the marking material particles are trapped within the softenable layer.
The word "agglomeration" as used herein is defined as the coming together and adhering of previously substantially separate particles, without the loss of identity of the particles.
The word "coalescence" as used herein is defined as the fusing together of such particles into larger units, usually accompanied by a change of shape of the coalesced particles towards a shape of lower energy, such as a sphere.
Generally, the softenable layer of migration imaging members is characterized by sensitivity to abrasion and foreign contaminants. Since a fracturable layer is located at or close to the surface of the softenable layer, abrasion can readily remove some of the fracturable layer during either manufacturing or use of the imaging member and adversely affect the final image. Foreign contamination such as finger prints can also cause defects to appear in any final image. Moreover, the softenable layer tends to cause blocking of migration imaging members when multiple members are stacked or when the migration imaging material is wound into rolls for storage or transportation. Blocking is the adhesion of adjacent objects to each other. Blocking usually results in damage to the objects when they are separated.
The sensitivity to abrasion and foreign contaminants can be reduced by forming an overcoating such as the overcoatings described in U.S. Pat. No. 3,909,262, the disclosure of which is totally incorporated herein by reference. However, because the migration imaging mechanisms for each development method are different and because they depend critically on the electrical properties of the surface of the softenable layer and on the complex interplay of the various electrical processes involving charge injection from the surface, charge transport through the softenable layer, charge capture by the photosensitive particles and charge ejection from the photosensitive particles, and the like, application of an overcoat to the softenable layer can cause changes in the delicate balance of these processes and result in degraded photographic characteristics compared with the non-overcoated migration imaging member. Notably, the photographic contrast density can degraded.
U.S. Pat. No. 4,536,458 (Ng), the disclosure of which is totally incorporated herein by reference, discloses a migration imaging member comprising a substrate and an electrically insulating softenable layer on the substrate, the softenable layer comprising migration marking material located at least at or near the surface of the softenable layer spaced from the substrate, and a charge transport molecule. The migration imaging member is electrostatically charged, exposed to activating radiation in an imagewise pattern, and developed by decreasing the resistance to migration, by exposure either to solvent vapor or heat, of marking material in depth in the softenable layer at least sufficient to allow migration of marking material whereby marking material migrates toward the substrate in image configuration. The preferred thickness of the softenable layer is about 0.7 to 2.5 microns, although thinner and thicker layers can also be utilized.
U.S. Pat. No. 4,536,457 (Tam), the disclosure of which is totally incorporated herein by reference, discloses a process in which a migration imaging member comprising a substrate and an electrically insulating softenable layer on the substrate, the softenable layer comprising migration marking material located at least at or near the surface of the softenable layer spaced from the substrate, and a charge transport molecule (e.g. the imaging member described in U.S. Pat. No. 4,536,458) is uniformly charged and exposed to activating radiation in an imagewise pattern. The resistance to migration of marking material in the softenable layer is thereafter decreased sufficiently by the application of solvent vapor to allow the light exposed particles to retain a slight net charge to prevent agglomeration and coalescence and to allow slight migration in depth of marking material towards the substrate in image configuration, and the resistance to migration of marking material in the softenable layer is further decreased sufficiently by heating to allow non-exposed marking material to agglomerate and coalesce. The preferred thickness is about 0.5 to 2.5 microns, although thinner and thicker layers can be utilized.
U.S. Pat. No. 4,970,130 (Tam et al.), the disclosure of which is totally incorporated herein by reference, discloses a xeroprinting process which comprises (1) providing a xeroprinting master comprising (a) a substrate and (b) a softenable layer comprising a softenable material, a charge transport material capable of transporting charges of one polarity and migration marking material situated contiguous to the surface of the softenable layer spaced from the substrate, wherein a portion of the migration marking material has migrated through the softenable layer toward the substrate in imagewise fashion; (2) uniformly charging the xeroprinting master to a polarity opposite to the polarity of the charges that the charge transport material in the softenable layer is capable of transporting; (3) uniformly exposing the charged master to activating radiation, thereby discharging those areas of the master wherein the migration marking material has migrated toward the substrate and forming an electrostatic latent image; (4) developing the electrostatic latent image; and (5) transferring the developed image to a receiver sheet. The process results in greatly enhanced contrast potentials or contrast voltages between the charged and uncharged areas of the master subsequent to exposure to activating radiation, and the charged master can be developed with either liquid developers or dry developers. The contrast voltage of the electrostatic latent image obtainable from this process generally initially increases with increasing flood exposure light intensity, typically reaches a plateau value of about 90 percent of the initially applied voltage even with further increase in flood exposure light intensity.
U.S. Pat. No. 5,215,838 (Tam et al.), the disclosure of which is totally incorporated herein by reference, discloses a migration imaging member comprising a substrate, an infrared or red light radiation sensitive layer comprising a pigment predominantly sensitive to infrared or red light radiation, and a softenable layer comprising a softenable material, a charge transport material, and migration marking material predominantly sensitive to radiation at a wavelength other than that to which the infrared or red light radiation sensitive pigment is sensitive contained at or near the surface of the softenable layer. When the migration imaging member is imaged and developed, it is particularly suitable for use as a xeroprinting master and can also be used for viewing or for storing data.
Migration imaging members are also suitable for other purposes, such as use as masks for exposing the photosensitive material in a printing plate for processes such as lithographic printing, and the like.
U.S. Pat. No. 5,102,756 (Vincett et al.), the disclosure of which is totally incorporated herein by reference, discloses a printing plate precursor which comprises a base layer, a layer of photohardenable material, and a layer of softenable material containing photosensitive migration marking material. Alternatively, the precursor can comprise a base layer and a layer of softenable photohardenable material containing photosensitive migration marking material. Also disclosed are processes for preparing printing plates from the disclosed precursors.
Copending application U.S. Ser. No. 08/353,461, entitled "Improved Migration Imaging Members", filed Dec. 9, 1994 with the named inventors Edward G. Zwartz, Carol A. Jennings, Man C. Tam, Philip H. Soden, Arthur Y. Jones, Arnold L. Pundsack, Enrique Levy, Ah-Me Hor, William W. Limburg, John F. Yanus, Damodar M. Pal, and Dale S. Renfer, the disclosure of which is totally incorporated herein by reference, discloses migration imaging member comprising a substrate, a first softenable layer comprising a first softenable material and a first migration marking material contained at or near the surface of the first softenable layer spaced from the substrate, and a second softenable layer comprising a second softenable material and a second migration marking material. Also disclosed is a migration imaging process employing the aforesaid imaging member.
Copending application U.S. Ser. No. 08/413,667, entitled "Improved Apparatus and Process for Preparation of Migration Imaging Members", filed Mar. 30, 1995 with the named inventors Philip H. Soden and Arnold L. Pundsack, the disclosure of which is totally incorporated herein by reference, discloses an apparatus for evaporation of a vacuum evaporatable material onto a substrate, said apparatus comprising (a) a walled container for the vacuum evaporatable material having a plurality of apertures in a surface thereof, said apertures being configured so that the vacuum evaporatable material is uniformly deposited onto the substrate; and (b) a source of heat sufficient to effect evaporation of the vacuum evaporatable material from the container through the apertures onto the substrate, wherein the surface of the container having the plurality of apertures therein is maintained at a temperature equal to or greater than the temperature of the vacuum evaporatable material.
Copending application U.S. Ser. No. 08/432,401, entitled "Pre-Sensitized Infrared or Red Light Sensitive Migration Imaging Members", filed May 1, 1995 with the named inventor Man C. Tam, the disclosure of which is totally incorporated herein by reference, discloses a process which comprises (1) providing a migration imaging member comprising a substrate, an infrared or red light radiation sensitive layer comprising a pigment predominantly sensitive to infrared or red light radiation, and a softenable layer comprising a softenable material, a charge transport material, and migration marking material predominantly sensitive to radiation at a wavelength other than that to which the infrared or red light sensitive pigment is predominantly sensitive contained at or near the surface of the softenable layer, said infrared or red light radiation sensitive layer being situated between the substrate and the softenable layer; (2) uniformly charging the imaging member; (3) subsequent to step (2), uniformly exposing the imaging member to activating radiation at a wavelength to which the migration marking material is sensitive; (4) subsequent to step (3), neutralizing charge on the surface of the imaging member spaced from the substrate, (5) subsequent to step (4), exposing the imaging member to infrared or red light radiation at a wavelength to which the infrared or red light radiation sensitive pigment is sensitive in an imagewise pattern, thereby forming an electrostatic latent image on the imaging member, wherein step (5) takes place at least 2 hours after completion of step (4); (6) subsequent to step (5), causing the softenable material to soften, thereby enabling the migration marking material to migrate through the softenable material toward the substrate in an imagewise pattern.
Copending application U.S. Ser. No. 08/432,291, entitled "Improved Migration Imaging Process", filed May 1, 1995 with the named inventors Man C. Tam and Edward G. Zwartz, the disclosure of which is totally incorporated herein by reference, discloses a process which comprises (a) providing a migration imaging member comprising (1) a substrate, (2) an infrared or red light radiation sensitive layer comprising a pigment predominantly sensitive to infrared or red light radiation, and (3) a softenable layer comprising a softenable material, a charge transport material, and a photosensitive migration marking material predominantly sensitive to radiation at a wavelength other than that to which the infrared or red light sensitive pigment is predominantly sensitive; (b) uniformly charging the imaging member; (c) subsequent to step (b), uniformly exposing the charged imaging member to a source of activating radiation with a wavelength to which the migration marking material is sensitive, wherein a filter comprising the infrared or red light radiation sensitive pigment is situated between the radiation source and the imaging member; (d) subsequent to step (b), exposing the imaging member to infrared or red light radiation at a wavelength to which the infrared or red light radiation sensitive pigment is sensitive in an imagewise pattern, thereby forming an electrostatic latent image on the imaging member; and (e) subsequent to steps (c) and (d), causing the softenable material to soften, thereby enabling the migration marking material to migrate through the softenable material toward the substrate in an imagewise pattern.
Copending application U.S. Ser. No. 08/432,448, entitled "Improved Overcoated Migration Imaging Members", filed May 1, 1995 with the named inventors Shadi L. Malhotra and Arthur Y. Jones, the disclosure of which is totally incorporated herein by reference, discloses a migration imaging member comprising (1) a substrate, (2) a softenable layer situated on the substrate, said softenable layer comprising a softenable material and a photosensitive migration marking material, and (3) an overcoating layer situated on the surface of the softenable layer spaced from the substrate, said overcoating layer comprising a material selected from the group consisting of: (a) polyacrylic acids, (b) poly (hydroxyalkyl methacrylates), (c) poly (hydroxyalkylacrylates), (d) vinyl alcohol-vinyl acetate copolymers, (e) vinyl alcohol-vinyl butyral copolymers, (f) alkyl celluloses, (g) aryl celluloses, (h) hydroxyalkyl cellulose acrylates, (i) hydroxyaryl cellulose acrylates, (j) hydroxyalkyl cellulose methacrylates, (k) hydroxyaryl cellulose methacrylates, (l) cellulose-acrylamide adducts, (m) poly (vinyl butyrals), (n) cyanoethylated celluloses, (o) cellulose acetate hydrogen phthalates, (p) hydroxypropylmethyl cellulose phthalates, (q) hydroxypropyl methyl cellulose succinates, (r) cellulose triacetates, (s) vinyl pyrrolidone-vinyl acetate copolymers, (t) vinyl chloride-vinylacetate-vinyl alcohol terpolymers, (u) ethylene-maleic anhydride copolymers, (v) styrene-maleic anhydride copolymers, (w) styrene-allyl alcohol copolymers, (x) poly(4-vinylpyridines), (y) polyester latexes, (z) vinyl chloride latexes, (aa) ethylene-vinyl chloride copolymer emulsions, (bb) poly vinyl acetate homopolymer emulsions, (cc) carboxylated vinyl acetate emulsion resins, (dd) vinyl acetate copolymer latexes, (ee) ethylene-vinyl acetate copolymer emulsions, (ff) acrylic-vinyl acetate copolymer emulsions, (gg) vinyl acrylic terpolymer latexes, (hh) acrylic emulsion latexes, (ii) polystyrene latexes, (jj) styrene-butadiene latexes, (kk) butadiene-acrylonitrile latexes, (ll) butadiene-acrylonitrile-styrene terpolymer latexes, (mm) propylene-acrylic acid copolymers, (nn) propylene-ethylene-acrylic acid terpolymers, (oo) poly (vinyl methyl ketones), (pp) poly (trimethyl hexamethylene) terephthalamides, (qq) chlorinated polypropylenes, (rr) poly (hexamethylene sebacates), (ss) poly(ethylene succinates), (tt) poly (caprolactams), (uu) poly (hexamethylene adipamides), (vv) poly (hexamethylene nonaneamides), (ww) poly (hexamethylene sebacamides), (xx) poly (hexamethylene dodecane diamides), (yy) poly (undecanoamides), (zz) poly (lauryllactams), (aaa) ethylene-methacrylic acid ionomers, and (bbb) mixtures thereof.
Copending application U.S. Ser. No. 08/432,380, entitled "Improved Migration Imaging Members", filed May 1, 1995 with the named inventor Shadi L. Malhotra, the disclosure of which is totally incorporated herein by reference, discloses a migration imaging member comprising (a) a substrate, (b) a softenable layer situated on one surface of the substrate, said softenable layer comprising a softenable material and a photosensitive migration marking material, and (c) an antistatic layer situated on the surface of the substrate opposite to the surface in contact with the softenable layer.
Copending application U.S. Ser. No. 08/442,227, entitled "Improved Migration Imaging Members", filed May 15, 1995 with the named inventors Shadi L. Malhotra, Liqin Chen, and Marie-Eve Perron, the disclosure of which is totally incorporated herein by reference, discloses a migration imaging member comprising (a) a substrate, (b) a softenable layer comprising a softenable material and a photosensitive migration marking material, and (c) a transparentizing agent which transparentizes migration marking material in contact therewith contained in at least one layer of the migration imaging member. Also disclosed is a process which comprises (1) providing a migration imaging member comprising (a) a substrate, (b) a softenable layer comprising a softenable material and a photosensitive migration marking material, and (c) a transparentizing agent which transparentizes migration marking material in contact therewith contained in at least one layer of the migration imaging member; (2) uniformly charging the imaging member; (3) subsequent to step (2), exposing the charged imaging member to activating radiation at a wavelength to which the migration marking material is sensitive; (4) subsequent to step (3), causing the softenable material to soften and enabling a first portion of the migration marking material to migrate through the softenable material toward the substrate in an imagewise pattern while a second portion of the migration marking material remains substantially unmigrated within the softenable layer, wherein subsequent to migration of the first portion of migration marking material, either (a) the first portion of migration marking material contacts the transparentizing agent and the second portion of migration marking material does not contact the transparentizing agent; or (b) the second portion of migration marking material contacts the transparentizing agent and the first portion of migration marking material does not contact the transparentizing agent.
Copending application U.S. Ser. No. 08/441,360, entitled "Method For Obtaining Improved Image Contrast In Migration Imaging Members", filed May 15, 1995 with the named inventors William W. Limburg, Joseph Mammino, George Liebermann, Clifford H. Griffiths, Michael M. Shahin, Shadi L. Malhotra, Liqin Chen, and Marie-Eve Perron, the disclosure of which is totally incorporated herein by reference, discloses a process which comprises (a) providing a migration imaging member comprising (1) a substrate and (2) a softenable layer comprising a softenable material and a photosensitive migration marking material present in the softenable layer as a monolayer of particles situated at or near the surface of the softenable layer spaced from the substrate; (b) uniformly charging the imaging member; (3) imagewise exposing the charged imaging member to activating radiation at a wavelength to which the migration marking material is sensitive; (d) subsequent to step (c), causing the softenable material to soften and enabling a first portion of the migration marking material to migrate through the softenable material toward the substrate in an imagewise pattern while a second portion of the migration marking material remains substantially unmigrated within the softenable layer; and (e) contacting the second portion of the migration marking material with a transparentizing agent which transparentizes migration marking material.
Copending application U.S. Ser. No. 08/432,747, entitled "Process and Apparatus for Manufacturing Migration Imaging Members", filed May 2, 1995 with the named inventors Hardy Sonnenberg, Arnold L. Pundsack, Man C. Tam, and Enrique Levy, the disclosure of which is totally incorporated herein by reference, discloses a process and apparatus for preparing migration imaging members. Two substrates with softenable layers applied to them travel through a vacuum chamber where they are simultaneously exposed to vapor deposition of the migration marking material. After the migration marking material is deposited, the two softenable layers are laminated together in the same vacuum chamber to form the migration imaging member. In one of the embodiments, the softenable layers are applied to the substrates in the same sweep of the substrate through the vacuum chamber vapor deposition and lamination steps.
Copending application U.S. Ser. No. 08/434,954, entitled "Film Loading Pins for External Drum Scanners", filed May 4, 1995 with the named inventors Robert J. Kleckner and Sandra Graveson, the disclosure of which is totally incorporated herein by reference, discloses a registration pin for a rotating drum recorder device which cooperates with a film to register and support the film during loading the film onto the drum. The registration pin has a reduced profile to reduce the overall size of the drum. The pin also has a construction to permit loading of different types of films onto the drum. The head of the registration pin is provided with a profile that supports and positions the film on the drum, even though the registration pin is shorter than conventional pins. The registration pin includes at least one protrusion to sandwich the film against the surface of the drum. The protrusion may take any appropriate form. The protrusion may include a "teardrop" shaped form, in order to positively hold the film on the drum.
Copending application U.S. Ser. No. 08/434,962, entitled "Modular Charging Device for Imaging System", filed May 4, 1995 with the named inventors Robert J. Kleckner, Irena Makarchuk, and Frank Martines, the disclosure of which is totally incorporated herein by reference, discloses a modular charging device for use in a printing or imaging system which includes a plurality of individual charging units and means for arranging the plurality of individual charging units together in a modular fashion. The modular charging device may be arc-shaped to uniformly charge a rotating drum or a circular belt, or may be linear to uniformly charge a linear imaging member.
Copending application U.S. Ser. No. 08/434,960, entitled "Film Heat Processor and Method of Developing Digital Film", filed May 4, 1995 with the named inventors Abu S. Islam, Robert J. Kleckner, Leo Chin, Hardy Sonnenberg, and Anthony Klein, the disclosure of which is totally incorporated herein by reference, discloses an apparatus and method of developing a heat developing film which includes a film support surface for supporting a film and heaters for developing the film supported on the film support surface. The film support surface may either be stationary or form part of a film transport. The film transport may either be a continuous film transport or a reciprocating film transport. The continuous film transport may be inclined or include an input pinch roller. In addition, the heaters may either be stationary, reciprocatable, or pivotable. The heaters are radiant heaters which may include a profiled heater output to control distortion of the film. The apparatus may be provided as a stand-alone unit or may be coupled, either externally to or within, a film exposure device.
Copending application U.S. Ser. No. 08/434,961, entitled "A Device that Uses Radiant Heat to Desensitize Migration Imaging Film and Allow Daylight Film Handling", filed May 4, 1995 with the named inventors Irena Makarchuk, Sandra Graveson, Robert J. Kleckner, Leo Chin, and Abu S. Islam, the disclosure of which is totally incorporated herein by reference, discloses a heating device for desensitizing migration imaging film on an external imaging member scanner. The heating device is curved and has a large surface area to provide maximum heating efficiency. The heating device is mounted to a bracket connected to a scanner cartridge and moves integrally with the scanner cartridge in the direction of the longitudinal axis of the imaging member. The heating device heats the migration imaging film to a temperature to ensure that the surface charge on the film is changed, but is less than a temperature needed for selenium particle migration. As a result, the selenium in the migration imaging film is no longer sensitive under daylight conditions. Thus, the migration imaging film can be removed and heated under daylight conditions providing a significant advantage over film that must be removed and heated under red light conditions.
While known imaging members and imaging processes are suitable for their intended purposes, a need remains for improved migration imaging members. In addition, a need remains for infrared or red light sensitive migration imaging members which can be prepared or manufactured with improved cost effectiveness. Further, there is a need for infrared or red light sensitive migration imaging members with improved resistance to scratching and other handling damage. Additionally, a need exists for infrared or red light sensitive migration imaging members wherein difficulties in applying an infrared or red light sensitive layer to the imaging member structure are reduced or eliminated. There is also a need for infrared or red light sensitive migration imaging members which, when imaged, exhibit improved optical density. In addition, there is a need for infrared or red light sensitive migration imaging members which exhibit improved uniformity of deposition of the infrared or red light sensitive material on the imaging member. Further, a need remains for infrared or red light sensitive imaging members wherein the need for a charge transport material in the softenable layer is reduced or eliminated. Additionally, a need remains for infrared or red light sensitive imaging members which exhibit reduced D.sub.min values, particularly in the ultraviolet region. There is also a need for infrared or red light sensitive imaging members for which the required exposure times are reduced. A need further remains for infrared or red light sensitive imaging members which exhibit increased charge life prior to imaging. In addition, there is a need for infrared or red light sensitive imaging members which require lower concentrations of infrared or red light sensitive pigment, thereby enabling reduced cost.